A typical modular conveyor belt is disclosed in U.S. Pat. 3,870,141 issued to J.M. Lapeyre on Mar. 11, 1975. According to this patent, substantially identical modules formed by injection molding are pivotally connected to one another to form a conveyor belt of a desired length. Each module includes a plurality of elongated elements, and each elongated element has a first pivot end and a second pivot end. The plurality of elongated elements are joined together such that the apertures defined in each of the first and second pluralities of pivot ends lie along a first and second pivot axis respectively which are parallel one to the other. The link ends of one module are intermeshed and pivotally connected by means of a pivot rod to the link ends of another module until an entire belt having the desired length is formed. Injection molded plastic belts built according to the teachings of this patent have been well received by industry and have many uses.
U.S. Pat. No. 4,051,949 issued on Oct. 4, 1977 also to Lapeyre, solved the problem of removing small and/or unstable articles from a conveyor belt without tipping over. The belt provides for a multiplicity of channels formed in the modules which receive the "teeth" of a comb to receive the articles. The belt disclosed in U.S. Pat. No. 4,171,045, also issued to Lapeyre, is similar to that of the U.S. Pat. No. 3,780,141 and U.S. Pat. No. 4,051,949 discussed above, except that selected ones of the vanes include a plurality of "dogs" which extend above the normal portion of the conveying surface to contact and push articles on the conveying surface along such that the belt will not slip underneath.
In a similar manner, U.S. Pat. No. 4,213,527 issued June 22, 1980 to J. M. Lapeyre, et al, further discloses a module for forming a link conveyor belt which has ridges or flight members extending transverse to the direction of travel for preventing the conveyor belt from slipping under articles riding on the conveyor belt surface. Similarly U.S. Pat. No. 4,170,281 issued on Oct. 19, 1979 and U.S. Pat. No. 4,080,842 issued on Mar. 22, 1978, both to Lapeyre, also show conveying belts having members extending transverse to the conveying surface for moving articles on the conveying surface along the belt such that the belt cannot slip underneath the article.
Other modular link conveyor belt patent applications or patents by J. M. Lapeyre and/or owned by the same assignee as the present invention include Ser. No. 483,210 entitled "Link Chain Belt" filed Apr. 14, 1983, and Ser. No. 179,523 entitled "Modular Center Drive Conveyor Belt" filed Aug. 19, 1980. More specifically, Application Ser. No. 118,309 which is a "Continuation" of Ser. No. 179,523 is directed to a separate "stop" or abutment member which prevents the pivot rod from moving axially out of the intermeshed link ends. Another Lapeyre patent is U.S. Pat. No. 4,556,142 entitled "Lightweight Modular Conveyor Belt" issued Dec. 3, 1985.
In addition, a patent application entitled "End-to-End Molded Conveyor Belt Module" filed Oct. 15, 1987 and having Ser. No. 110,109 discloses modules which may be "end-to-end molded."
Another conveyor belt designed particularly for changing horizontal directions or flexing is disclosed in U.S. Pat. Nos. 4,153,152 and U.S. Pat. No. 4,184,588 also issued to J. M. Lapeyre on May 8, 1979 and Jan. 22, 1980 respectively.
U.S. Pat. No. 4,709,807 issued to Poerink on Dec. 1, 1987 discloses the use of pegs and/or dowels as closing or "stop" devices which are inserted in the outboard sleeve type link ends to prevent the transverse pivot rods from coming out.
In a similar manner, Maglio et al discloses in U.S. Pat. No. 3,726,569 issued Apr. 10, 1973, the use of various types of end plugs which either cut into or are received into the "sleeve" member to prevent the connecting rod from working its way out.
The "All-in-One"(R) conveyor belt manufactured by the KVP Company in Sacramento, California and illustrated in FIG. 4 of U.S. Pat. No. 4,742,907 issued May 10, 1988 to Karl V. Palmaer, is a modular plastic belt driven at a central transverse connecting member which can be brick-layed, and therefore can be provided in different widths.
A plastic modular belt sold by the Cambridge Wire Cloth Company of Cambridge, Md. under the name of Cam-Clean.RTM. and substantially described in U.S. Pat. No. 4,557,374 issued on Dec. 10, 1985 to Robert H. Bode is driven in the center area of a module by a sprocket tooth received by a recess in the module defined by a pair of transverse connecting members.
Finally, the Rexnord Corp. of Milwaukee, Wis. has recently introduced a group of plastic conveyor belts designated as the "5900" series which uses individual and separate snap-in plugs to retain "headless" pivot rods in position.
Thus, a review of the prior art patents and commercial belts as well as pending applications of the assignee of the present invention reveals that to date there has not been an easy, simple and inexpensive technique for maintaining the pivot rods in position in assembled modular conveying belts. More particularly, none of the prior art conveying belts are capable of being repaired or assembled by non-destructive removal of the pivot rods, except for those which require separate abutment or "stop" members which must be individually inserted at each pivot rod. Therefore, it is an object of this invention to provide conveyor belts wherein the modules can be repaired or disassembled without destruction of the pivot rod, and thereby allow reuse of the pivot rods.
It is another object of the present invention to provide a module for forming a conveyor belt which is modular and has the inherent capability of being easily repaired and replaced.
It is also an object of the present invention to provide a conveyor belt which is simple, easy, and inexpensive to construct and does not require separate "plugs" to retain the pivot rods in position.